Color Pattern Research Articles

A subspecies of marbled newt (Triturus marmoratus) in the Iberian Peninsula newly resolved from congruent nuclear and mitochondrial dna data

Abstract The herpetofauna of the Iberian Peninsula is relatively well-researched, yet detailed studies, at least in part relying on molecular genetic data, continue to reveal taxa new to science, mostly species and subspecies. Newts of the genus Triturus are one such group with undiscovered yet taxonomically relevant variation, as shown by the recent description of new (sub)species of pygmy newts (T. pygmaeus, T. rudolfi). The marbled newt, Triturus marmoratus, shows an equally deep and geographically coherent spatial-genetic diversification. It is here shown that a northern and a southern group are characterized by different mitochondrial dna profiles and are also differentiated in morphometry and colouration pattern. With no firm evidence for selection against intermediate genotypes, the southern group is described at the subspecies level, as T. marmoratus harmannis ssp. nov. The subspecies’ contact zone is situated at ca. 41.5 northern latitude and stretches from the Atlantic coast near Porto, Portugal to the northeast of Madrid, Spain.

Eastern Black Kingsnake Lampropeltis nigra dorsal scale colouration primarily adapted for thermoregulation

The Eastern Black Kingsnake Lampropeltis nigra exhibits variation in colouration and pattern throughout its range. Drivers behind this colour variation remain largely unknown. To elucidate patterns in the percentage of light pigmentation in L. nigra dorsal scales (% light) we compared two primary hypotheses. Our first hypothesis posited that L. nigra colouration has been adapted for thermoregulation (thermoregulation). Alternatively, we hypothesised that L. nigra colouration has been adapted to avoid detection by predators and prey (crypsis). To test our hypotheses, we modeled L. nigra % light from 46 counties within Mississippi as a function of average temperature, average maximum temperature (thermoregulation) and soil value (darkness of soil colour; crypsis). We included percentage forest cover as a modifying variable in the thermoregulation hypothesis and an interacting variable in the crypsis hypothesis. The best competing model included average temperature and percent forest cover as explanatory variables (LOOIC = -291.3, weight = 0.84, Bayesian R2 = 0.37 [fixed] and 0.55 [total]). There was a positive relationship between % light and average temperature (β = 0.23, 95% CIs = 0.13, 0.34) and average maximum temperature (β = 0.11, 95% CIs = -0.00, 0.21), and a negative relationship with percent forest cover (β = -0.14, 95% CIs = -0.23, -0.04). These results support the thermoregulation hypothesis. The climate in Mississippi, as in most of the world, is expected to experience shifts over the next century. If ambient temperatures experienced through these changes are outside of L. nigra’s thermal optima, as based on colour patterns and relationships observed in our study, then behavioural adaptations may result in some individuals experiencing thermal advantages that influence this species’ distribution. The patterns observed in our study, and expected changes in L. nigra behaviour and distribution, are likely to occur among other ectothermic species with relatively static colouration. Keywords: Colour adaptation, homeostasis, Mississippi

Review of the Voluta musica Complex

The distinctive morphology, color pattern, and isolated geographic locations of the various proposed taxa of the Voluta musica complex are discussed and specimens of the various taxa are illustrated. From the Miocene to the present, during interglacial times and the associated higher sea levels during the Neogene, evidence shows that populations of ancestral V. musica had become genetically isolated on offshore islands resulting in a species swarm of closely-related allopatric species. The following taxa are recognized as full species, and these include: Voluta musica, V. carneolata, V. thiarella, V. damula, and V. typica.

Robust And Discriminant Local Color Pattern (RADLCP): A novel color descriptor for face recognition

In [1] Karanwal et al. introduced the novel color descriptor in Face Recognition (FR) called as Fused Local Color Pattern (FLCP). In FLCP, the RGB color format is utilized for extracting features. From R, G and B channels, the MRELBP-NI, 6 × 6 MB-LBP and RD-LBP are imposed for feature extraction and then all are integrated to form the FLCP size. FLCP beats the accuracy of various methods. The one major shortcoming observed in [1] is that the basic format RGB is used for extracting features. Literature suggests that other hybrid formats achieves better recognition rates than RGB. Motivated from literature, the proposed work uses the hybrid color space format RCrQ for feature extraction. In this format R channel is taken from RGB, Cr channel is taken from YCbCr and Q channel is taken from YIQ. On R channel, MRELBP-NI is imposed for extracting features, On Cr channel 6 × 6 MB-LBP is imposed and on Q channel RD-LBP is imposed for extracting features. Then all channel features are joined to build the robust and discriminant feature called as Robust And Discriminant Local Color Pattern (RADLCP). Compression and matching is assisted from PCA and SVMs. For evaluating results GT face dataset is used. Results proves the potency of RADLCP in contrast to gray scale based implemented descriptors. RADLCP also beats the results of FLCP. Several literature techniques are also outclassed by RADLCP. For evaluating all the results MATLAB R2021a is used.

Integrating ecological niche modeling and rates of evolution to model geographic regions of mimetic color pattern selection

Geographic variation in natural selection derived from biotic sources is an important driver of trait evolution. The evolution of Müllerian mimicry is governed by dual biotic forces of frequency-dependent predator selection and densities of prey populations consisting of conspecifics or congeners. Difficulties in quantifying these biotic forces can lead to difficulties in delimiting and studying phenomena such as mimicry evolution. We explore the spatial distribution of morphotypes and identify areas of high mimetic selection using a novel combination of methods to generate maps of mimetic phenotype prevalence in Ranitomeya poison frogs, a group of frogs characterized by great phenotypic variation and multiple putative Müllerian mimic pairs. We categorized representative populations of all species into four major recurring color patterns observed in Ranitomeya: striped, spotted, redhead, and banded morphs. We calculated rates of phenotypic evolution for each of the 4 morphs separately and generated ecological niche models (ENMs) for all species. We then split our species-level ENMs on the basis of intraspecific variation in color pattern categorization, and weighted ENM layers by relative evolutionary rate to produce mimicry maps. Our phenotypic evolutionary rate analyses identified multiple significant shifts in rates of evolution for the spotted, redhead, and banded phenotypes. Our mimicry maps successfully identify all suspected and known areas of Müllerian mimicry selection in Ranitomeya from the literature and show geographic areas with a gradient of suitability for Müllerian mimicry surrounding mimic hotspots. This approach offers an effective hypothesis generation method for studying traits that are tied to geography by explicitly connecting evolutionary patterns of traits to trends in their geographic distribution, particularly in situations where there are unknowns about drivers of trait evolution.

Post-Juvenile Moult of the Red Crossbill Loxia curvirostra: Differences in Relation to Sex and Colour Patterns

Post-Juvenile Moult of the Red Crossbill Loxia curvirostra: Differences in Relation to Sex and Colour Patterns

Impacts of Emergency Vehicle Marking Characteristics and Wearable Lights on Driver Responses

Retroreflective markings provide important visual information to drivers about emergency vehicles and the incidents at which they are working. A stationary outdoor field study to investigate the impacts of emergency vehicle marking color, retroreflectivity level, and spatial patterns on drivers’ ability to see nearby emergency responders was carried out. The study also examined the impacts of a wearable flashing light-emitting diode (LED) light. Based on the results, agencies should use materials with higher levels of retroreflectivity carefully, especially when they will be covering large-area vehicle surfaces. Limiting the maximum retroreflectivity level to no greater than American Society for Testing and Materials Type III may help lessen negative impacts of bright reflective materials on drivers’ ability to see emergency responders. As long as the average reflectivity of different color combinations is similar to that of red and yellow reflective markings, chevron patterns with those color combinations will not reduce emergency responder visibility. Outline patterns of reflective markings on vehicles performed similarly at night to patterns covering most of the vehicle surface. The effectiveness of using high-retroreflectivity materials in an outline pattern in combination with lower- (or non-) retroreflectivity materials elsewhere on the surface should be studied. Wearable flashing LED lights can make emergency responders easier to see at night, provided they do not increase glare to approaching drivers.

Temperature differently affects body pigmentation of the paper wasp Polistes dominula along an urban and a wider geographical gradient

In insects, different pigments, such as melanins and pterins, are involved in thermoregulation. The degree of melanisation often varies along geographical gradients, according to the so-called thermal melanism hypothesis, i.e. darker forms are found in colder places because they can warm up more quickly. Similarly, pterins work as heat sinks and thus are expected to be more abundant in colder sites. Cities, which are warmer than surrounding areas (Urban Heat Island (UHI) effect), might also be expected to influence pigmentation, although studies are lacking. Here, we sampled workers of the social paper wasp Polistes dominula (Christ, 1791) (Vespidae) across an urbanisation gradient in an Italian metropolis and used iNaturalist pictures of this species across Italy to study pigmentation patterns at both urban and larger geographical scales. We found a lower yellow intensity of abdominal spots at warmer locations. Scanning Electron Microscopy strongly suggested that yellow colouration is due xanthopterin, known to be the heat sink molecule in other social vespids. Thus, wasps from warmer (i.e., urban) environments are likely to have fewer xanthopterin granules, in line with the lack of need for heat storage due to the local thermal gradient (UHI effect). At the country level, we found that wasps at higher latitudes had smaller yellow spots on the thorax and only two spots instead of four at higher altitudes, in full accordance with the thermal melanism hypothesis. In conclusion, climatic conditions seem to affect insect colour patterns both along urban and wider geographical gradients, although colour changes may affect different body parts and pigments likely according to different needs.

Ancestry dynamics and trait selection in a designer cat breed

The Bengal cat breed was developed from intercrosses between the Asian leopard cat, Prionailurus bengalensis, and the domestic cat, Felis catus, with a last common ancestor approximately 6 million years ago. Predicted to derive ∼94% of their genome from domestic cats, regions of the leopard cat genome are thought to account for the unique pelage traits and ornate color patterns of the Bengal breed, which are similar to those of ocelots and jaguars. We explore ancestry distribution and selection signatures in the Bengal breed by using reduced representation and whole-genome sequencing from 947 cats. The mean proportion of leopard cat DNA in the Bengal breed is 3.48%, lower than predicted from breed history, and is broadly distributed, covering 93% of the Bengal genome. Overall, leopard cat introgressions do not show strong signatures of selection across the Bengal breed. However, two popular color traits in Bengal cats, charcoal and pheomelanin intensity, are explained by selection of leopard cat genes whose expression is reduced in a domestic cat background, consistent with genetic incompatibility resulting from hybridization. We characterize several selective sweeps in the Bengal genome that harbor candidate genes for pelage and color pattern and that are associated with domestic, rather than leopard, cat haplotypes. We identify the molecular and phenotypic basis of one selective sweep as reduced expression of the Fgfr2 gene, which underlies glitter, a trait desired by breeders that affects hair texture and light reflectivity.

Deep divergences among inconspicuously colored clades of Epipedobates poison frogs

Poison frogs (Dendrobatidae) are famous for their aposematic species, having a combination of diverse color patterns and defensive skin toxins, yet most species in this family are inconspicuously colored and considered non-aposematic. Epipedobates is among the youngest genus-level clades of Dendrobatidae that includes both aposematic and inconspicuous species. Using Sanger-sequenced mitochondrial and nuclear markers, we demonstrate deep genetic divergences among inconspicuous species of Epipedobates but relatively shallow genetic divergences among conspicuous species. Our phylogenetic analysis includes broad geographic sampling of the inconspicuous lineages typically identified as E. boulengeri and E. espinosai, which reveals two putative new species, one in west-central Colombia (E. sp. 1) and the other in north-central Ecuador (E. aff. espinosai). We conclude that E. darwinwallacei is a junior subjective synonym of E. espinosai. We also clarify the geographic distributions of inconspicuous Epipedobates species including the widespread E. boulengeri. We provide a qualitative assessment of the phenotypic diversity in each nominal species, with a focus on the color and pattern of inconspicuous species. We conclude that Epipedobates contains eight known valid species, six of which are inconspicuous. A relaxed molecular clock analysis suggests that the most recent common ancestor of Epipedobates is ∼11.1 million years old, which nearly doubles previous estimates. Last, genetic information points to a center of species diversity in the Chocó at the southwestern border of Colombia with Ecuador. A Spanish translation of this text is available in the supplementary materials.

Automated workflows using Quantitative Colour Pattern Analysis (QCPA): a guide to batch processing and downstream data analysis

Animal and plant colouration presents a striking dimension of phenotypic variation, the study of which has driven general advances in ecology, evolution, and animal behaviour. Quantitative Colour Pattern Analysis (QCPA) is a dynamic framework for analysing colour patterns through the eyes of non-human observers. However, its extensive array of user-defined image processing and analysis tools means image analysis is often time-consuming. This hinders the full use of analytical power provided by QCPA and its application to large datasets. Here, we offer a robust and comprehensive batch script, allowing users to automate many QCPA workflows. We also provide a complimentary set of useful R scripts for downstream data extraction and analysis. The presented batch processing extension will empower users to further utilise the analytical power of QCPA and facilitate the development of customised semi-automated workflows. Such quantitatively scaled workflows are crucial for exploring colour pattern spaces and developing ever-richer frameworks for analysing organismal colouration accounting for visual perception in animals other than humans. These advances will, in turn, facilitate testing hypotheses on the function and evolution of vision and signals at quantitative and qualitative scales, which are otherwise computationally unfeasible.

Color Authenticity for the Sustainable Development of Historical Areas: A Case Study of Shiquan

Currently, historical areas in China are facing issues of color authenticity and excessive commercialization. Colors, as an important element of historical areas, reflect their history and culture. However, there are some flaws in the existing research methods, so a more scientific and systematic method is needed to obtain accurate and objective color visualization results to promote the sustainable development of historical areas. In order to explore the methods and applications of visualizing the environmental color patterns of historical areas, Shiquan Street in Suzhou, China, was taken as the research object; ArcGIS 10.5 was used to obtain the street-view photo samples; Matlab was used to summarize the architectural colors of the historical areas; and K-means clustering was used to generate the central color card of the historical areas, thus completing the color visualization of the historical areas, followed by further searching for the color patterns and central colors, so as to explore the strategies for sustainable development of historical areas. The various quantified color models of historical areas can explore the regional uniqueness and color locality of historical areas, which avoids problems such as homogenization of block colors, unclear styles and features, and an excessive proportion of commercial colors caused by poor color guidance and control in the design related to historical areas, providing approaches to the research on the harmonious unity of environmental colors and features related to historical areas. A color-based research method has been proposed to protect and maintain the original appearance of historical areas. The application of this method provides a new perspective and possibility for the protection of historical areas, allowing these areas to achieve historical sustainability while maintaining their historical characteristics and values.

Transcriptomic and Physiological Analysis Reveal Melanin Synthesis-Related Genes and Pathways in Pacific Oysters (Crassostrea gigas).

Shell color is one of the shell traits of molluscs, which has been regarded as an economic trait in some bivalves. Pacific oysters (Crassostrea gigas) are important aquaculture shellfish worldwide. In the past decade, several shell color strains of C. gigas were developed through selective breeding, which provides valuable materials for research on the inheritance pattern and regulation mechanisms of shell color. The inheritance patterns of different shell colors in C. gigas have been identified in certain research; however, the regulation mechanism of oyster pigmentation and shell color formation remains unclear. In this study, we performed transcriptomic and physiological analyses using black and white shell oysters to investigate the molecular mechanism of melanin synthesis in C. gigas. Several pigmentation-related pathways, such as cytochrome P450, melanogenesis, tyrosine metabolism, and the cAMP signaling pathway were found. The majority of differentially expressed genes and some signaling molecules from these pathways exhibited a higher level in the black shell oysters than in the white, especially after L-tyrosine feeding, suggesting that those differences may cause a variation of tyrosine metabolism and melanin synthesis. In addition, the in vitro assay using primary cells from mantle tissue showed that L-tyrosine incubation increased cAMP level, gene and protein expression, and melanin content. This study reveals the difference in tyrosine metabolism and melanin synthesis in black and white shell oysters and provides evidence for the potential regulatory mechanism of shell color in oysters.

Morphological and genetic diversification of pygmy and marbled newts, with the description of a new species from the wider Lisbon Peninsula (Triturus, Salamandridae)

Abstract Iberian populations of large-bodied newts, with Triturus marmoratus in the north and T. pygmaeus in the south of the peninsula, were studied for external morphology, mitochondrial dna and for a panel of single nucleotide polymorphisms. This confirmed the species’ low level of interspecific hybridization and their parapatric, mosaic-like mutual range border across the peninsula. The genetic data also revealed substantial variation within T. pygmaeus, with narrow (0.43–35.2 km) clinal transitions in the very centre of Portugal. Similar clines were observed for body size and colouration pattern. Pygmy newts in the west of Portugal are larger, with a more striped (less reticulated) green dorso-lateral colouration pattern than those in the east and south of the country. The western group of populations is described as a new species, Triturus rudolfi sp. nov., on account of a long, ca. 2.5 Ma, independent evolutionary history and limited hybridization with its sister-species T. pygmaeus, suggesting selection against hybrid offspring. The range of the newly described species may be restricted to the wider Lisbon Peninsula, stretching northwards along the Atlantic coast to the river Vouga estuary. Inland, the range border may be set by the lower Tejo River, or by the currently wide area of agricultural land at either side of that river, that may accommodate a residual hybrid zone. The close contact between both pygmy newt species is effectively limited to a ca. 20 × 40 km area directly north of the town Entroncamento, where T. rudolfi sp. nov. is sandwiched in between T. marmoratus and the river Tejo.

Chitin‐Based Functional Films for the Colorimetric Detection of Ethylene Glycol

A new method is developed for producing large‐area color thin films for the colorimetric detection of ethylene glycol. This method is based on thermal evaporation of chitin. This process enables easy manipulation of the thickness and color patterns of the film by using shadow masks and repeated evaporation. This film is used to demonstrate a colorimetric sensor for the detection of ethylene glycol gas. The use of chitin allows the manufacture of inexpensive and environment‐friendly gas detectors. When the film is exposed to target gas, the film reacts with ethylene glycol and hydroxyl group on the chitin‐film by etherification. Then the films undergo both chemical and structural changes, resulting in color changes at low ppm concentrations. It is able to compare the sensor reaction to gases with and without the hydroxyl group. The selectivity of the sensor is confirmed by analyzing the gas containing the hydroxyl group through the linear discriminant analysis (LDA) method. It is expected that the results will be utilized to provide low‐cost and low‐power systems for gas monitoring.

Color Patterns And Enhanced Texture Learning For Detecting Computer-Generated Images

Abstract Detection of computer-generated (CG) images can reveal the authenticity and originality of digital images. However, recent cutting-edge image generation methods make it very difficult to distinguish CG images from natural photographs. In this paper, a novel method based on color patterns and enhanced texture learning is proposed to tackle this problem. We designed and implemented the backbone network with a separation-fusion learning strategy by constructing a multi-branch neural network. The luminance and chrominance patterns in dual-color spaces (RGB and YCbCr) are leveraged to achieve a robust representation of image differences. A channel-spatial attention module and a global texture enhancement module are also integrated into a backbone network to enhance the learning of inherent traces. Experiments on several commonly used benchmark datasets and a newly constructed dataset with more realistic and diverse images demonstrate that the proposed algorithm outperforms state-of-the-art competitors by a large margin.

Breads formulated with avocado pulp powder as a fat substitute: Quality parameters and in vitro inhibition activities.

The aim of the current study was to evaluate the influence of increasing contents (5%-25%) of avocado pulp powder (APP) produced by foam-mat drying (FMD) as a substitute for hydrogenated vegetable fat in bread on its nutritional composition, physical properties, α-amylase, α-glucosidase, and lipase inhibition, total phenolic content, antioxidant activity, color, structure, and x-ray diffraction patterns. The increase in the APP content decreased the values of lipids, carbohydrates, energy, firmness, and specific volume of breads. The inhibition of lipase activity showed a pronounced increase, while the total phenolic content and antioxidant activity were significantly elevated. The color parameters a* and b* were higher in the breads with added APP. The crystalline structure transitioned from type A to type V with 15% APP incorporation. Taken together, these results suggest that APP has potential to act as a healthier substitute for saturated fats in breads, paving the way to develop creative and innovative solutions for the functionalization of bakery food products.

DNA Barcoding Supports "Color-Pattern''-Based Species of Stictochironomus from China (Diptera: Chironomidae).

The genus Stictochironomus (Diptera: Chironomidae) has an almost worldwide distribution, with more than 30 species. However, species delimitation and identification based on the markings on the wings and legs are controversial and uncertain. In this study, we focused on color patterns to review the adults of the genus from China, and two new species (S. trifuscipes sp. nov. and S. quadrimaculatus sp. nov.) are described and figured. DNA barcodes can accurately separate the two new species with specific color patterns. However, heterospecific individuals form a monophyletic cluster in the phylogeny tree. For example, S. maculipennis (Meigen) and S. pictulus (Meigen), which have a lower interspecific genetic divergence, form a single clade. Sequences with the same species name but with high intraspecific distance form more than one phylogenetic clade, such as S. sticticus (Fabricius) of three clades, S. pictulus of four clades, S. akizukii (Tokunaga) and S. juncaii Qi, Shi, and Wang of two clades, might have potential cryptic species diversity. Species delimitation analysis using ASAP, PTP, and GMYC clearly delineated them as separate species. Consequently, color patterns are a good diagnostic characteristic for species delimitation in Stictochironomus. The distance-based analysis shows that a threshold of 4.5-7.7% is appropriate for species delimitation in Stictochironomus. Additionally, an updated key including color pattern variation for male adults of known Stictochironomus species from China is provided.

Sticky Multicolor Mechanochromic Labels.

Sticky-colored labels are an efficient way to communicate visual information. However, most labels are static. Here, we propose a new category of dynamic sticky labels that change structural colors when stretched. The sticky mechanochromic labels can be pasted on flexible surfaces such as fabric and rubber or even on brittle materials. To enhance their applicability, we demonstrate a simple method for imprinting structural color patterns that are either always visible or reversibly revealed or concealed upon mechanical deformation. The mechanochromic patterns are imprinted with a photomask during the ultraviolet (UV) cross-linking of acrylate-terminated cholesteric liquid crystal oligomers in a single step at room temperature. The photomask locally controls the cross-linking degree and volumetric response of the cholesteric liquid crystal elastomers (CLCEs). A nonuniform thickness change induced by the Poisson's ratio contrast between the pattern and the surrounding background might lead to a color-separation effect. Our sticky multicolor mechanochromic labels may be utilized in stress-strain sensing, building environments, smart clothing, security labels, and decoration.

Analysing biological colour patterns from digital images: An introduction to the current toolbox.

Understanding the numerous roles that colouration serves in the natural world has remained a central focus in many evolutionary and ecological studies. However, to accurately characterise and then compare colours or patterns among individuals or species has been historically challenging. In recent years, there have been a myriad of new resources developed that allow researchers to characterise biological colours and patterns, specifically from digital imagery. However, each resource has its own strengths and weaknesses, answers a specific question and requires a detailed understanding of how it functions to be used properly. These nuances can make navigating this emerging field rather difficult. Herein, we evaluate several new techniques for analysing biological colouration, with a specific focus on digital images. First, we introduce fundamental background knowledge about light and perception to be considered when designing and implementing a study of colouration. We then show how numerous modifications can be made to images to ensure consistent formatting prior to analysis. After, we describe many of the new image analysis approaches and their respective functions, highlighting the type of research questions that they can address. We demonstrate how these various techniques can be brought together to examine novel research questions and test specific hypotheses. Finally, we outline potential future directions in colour pattern studies. Our goal is to provide a starting point and pathway for researchers wanting to study biological colour patterns from digital imagery.